Automatic telephone system



Nov. 22, 1938. a. D. wxLLls AUTOMATIC' TELEPHONE S'STEM Filed Oct. 7, 1935 5 Sheets-Sheet l Nov. 22, 1938. B. D. wlLLls 2,137,431

AUTOMATIC TELEPHONE SYSTEM Filed oct. 7. 1935 s sheets-sheet 2 INVENTOR. BERNARD D. WILLIS ATTORNEY.

vBY

FINDE BANK 5 NOV. 22, 1938. B, D, w|L| |S Y 2,137,431

AUTQMATIC TELEPHONE SYSTEM Filed oet. 7, 1935 l3 sheets-sheet 5 `lm 2 t ge 0n S` s 'e im INVENTOR. SQ BERNARD D. w/LL/s ATTORNEY.

Patented Nov. 22, 193s 2,137,43l

UNITED STATES PATENT Norties AUTMATIC TELEPHONE SYSTEM Bernard D. Willis, Oak Park, Ill., assigner, `by

mesne assignments, to Associated Electric Laboratories, Inc., Chicago, I-ll., a corporation kof Delaware Application October 7, 1,9135, Serial No. 43,903

17 Claims. (Gl. 179-18) 'Ihe Apresent invention relates in general to route, shown in Fig. 3, these switches vcomprise automatic telephone systems, and more especially trunk iinders such as F', arranged in several to systems of lthe type which employ separate groups, rst selectors such as SI and second setting and speaking routes, commonly known as selectors such as S2. The selectors may be of `5 by-pass systems. The object of the invention is the Strowger type, preferably, The trunk find- V5 to provide Aa new and improved system of this erS. such as F may be rotary Single mOiiOrl iirldcharacter `which is better adapted to present ers, and if each nder has ecess to ftyirunks, commercial requirements than those heretofore as is usual in the case of rotary finders, there available. would be four groups required to take care of r1.0 'The invention will be described hereinafter two-hundred trunk circuits TC. k10 with reference to the accompanying drawings, 'rhe equipmentinvoived having been described,

AcomprisingFigs. 1, 2, and 3, which show by means the Operation Oi the system will be explained. of the usual circuit diagrams suiiicient of the F01 this pllrDQSe vit Will be assumed that the Subequipment involved to enable the invention to criber ,et Steiifirl A desires t0 Set 11p e Connec- ,l lbefexplained and understood. `tion to the Aline .of station B. Upon the removal :l5

Referring to the drawings, Fig. l shows at the 10i the receiver at statiOn A a bridge iS ClOSed left a subscribers station A, having a line exeCrOSS lirle C OildlleOrS 2 .and 3 and the lirle relay tendingto the exchange and there equipped with 1.4 is energized. On energizetion. the line relay `the usual line and cut-off relays. connects'the cut-off relay 5 to multiple test con- 20 The Aline of station A may be one of a group ldCS Sllll es 3 in the finder banks and grOllrldS .29 of two-hundred lines which are accessible to a ille Start Wiregl Through the medium of the groupof connectors and also to a group of iinddiStriblltOr D er1 idle `iirider' iS 110W Started 11D iIl ers, preferably ofthe Strowger type. Fig. l in- Search 0f lille Calling line. Assuming the nder dicates one iinder of the group, denoted by the F iS used, the Swifeh .iS rSi Operated Virl its vertics reference character F, and also a distributor D `@al motion under control of vertical test Wiper 2,5 which is common to the group. The nder and itl, end Ellen irl its rOtery motion under the 60ndistributor may have any well known circuit brel OfitS files-. Wiper ll, end iS SODPed When the arrangement and hence the detailed circuits are letter Wiper reaches test Contact 8 of the calling not shown. The Saunders Patent No. 1,851,132, line. At this point the rlder Cesi relay erler- 30 granted March 29, 1932, shows a finder system gizes in series with the cut-0H relay 5, the latter 3.0 that maybe used. relay energizing also. On energizing, relay 5 Associated with the lnder F is a, trunk circuit locks itself to the test lead coming from the nd- TC which comprises the relays shown and a er and also connects this test lead to the test step-b y-step sender SD. lead 6 extending to the connector banks, where 3,5 TheA trunk circuit TC is accessible to a number the calling line is made busy. Relay 5 also dis- 35 of so-called confluence switches such as CS, connects the line relay 4, permitting it to deenerwhich are also preferably of the Strowger type. giZe.

The switch CS has access 'to two hundred trunk The calling line conductors 2 and 3 are thus circuits such as TC. Assuming that sixteen trunk extended through by way of bank contacts l 4 0 circuits, or finders such as F, are required for and 9, and finder wipers lll and l2, to the line 4 0 each group of subscribers lines, the arrangement relay l5 irl ille lillli'lk Circuit TC, Where the Said shown comprising a single group of conuence relay I6 iS eCCOrdingly energized. Orl energiZiIlg, switchesgives a capacity of twelve groups of line relay it grounds the conductor 25 at 21 to subscribers lines, or 2400 lines, with eight trunks provide a holding circuit for the finder F and cut- A5 remaining which can be allotted to additional Off relay 5, Connects the Clit-Off relay l1 130 the 155 nders in busy groups if required. test lead 33 at 2%, and at 29 grounds the finder Fig. 2 shows a connector switch C, having acstart lead 30. `cess rto two-hundred subscribers lines one of As a result of the grounding of the start lead which is the line of station B. The connector 3G, the start relay IUI irl the trunk finder F' so c may be directly paired with the connuence pulls up. prepares the test circuit et |09, Closes e0 4 switches CS, as 'shown in vthe drawings. There a circuit for the lower polarizing winding of test are, of course, as many groups of connectors as relay |02 at the same point, and closes a circuit there are groups of subscribers lines, and each for stepping Vmagnet H14 at IIU. On energizing, connector `has an associated conuence switch. the stepping magnet I 04 closes a circuit for @s Considering ,now the switches in the setting stepping relay |03, which energizes and breaks 45,5

the circuit of magnet |04, the latter falling back and advancing the nder wipers |05-|08 one step. This interaction of magnet |04 and relay |03 continues, and the nder Wipers are advanced step by step, until the test Wiper |01 en- Y gages the test contact |1, where it finds a batlas tery potential on conductor 33. As a result the stepping relay |03 is held energized, and relays 02 and |1 are energized in series over a test circuit which extends from ground at |09 by way of |02, |03, |01, ||1, 33, contacts controlled byY 39, 28, and |1 to battery.

Considering rst the effect of energizing relay I1, this relay locks itself at 36, closes the finder holding circuit at 35, opens the start circuit at 31, and at its outer. contacts disconnects the line relay |6, which falls back. By this time, however, the lead 33 has direct ground on it, as will subsequently appear, and the finder holding circuit is maintained over 33, contacts controlled by 39, 35, and 25.

At the finder F', the holding up of relay |03 prevents the possibility of reclosing the circuit of magnet |04 and insures a positive stopping of the finder. Test relay |02, on energizing, breaks the circuit of magnet |04 at I |5, transfers the finder start circuit at ||6, and closes its contacts ||3 and ||4. The effect of closing these two contacts is to short circuit the upper windings of relays |02 and |03 and to connect the test lead 33 to test lead |23. Since the upper windings ofrelays |02 and |03 are short-circuited the test lead 33 will be grounded at |09 until the slow-acting start relay |0| falls back. Relay |02 ris held energized over its lower or polarizing winding, which is able to maintain the relay after it is once operated. Relay |03 falls back.

The test relay |02 also extends the line conductors 3| and 32 by way of wipers |05 and |06 and contacts and ||2 to the windings of the line relay |24 of the first selector SI. The line relay accordingly energizes and closes a circuit for the slow-acting release relay |25, which energizes in turn and places ground on the test lead |23, thereby completing a holding circuit including conductors |23, 33 and 25. The release relay grounds this circuit before relay |0| has had time to fall back.

Due to ground on the conductor |23 the Slowacting changeover relayv |26 also energizes at this time, .and connects the dial tone circuit to the lower winding of line relay |24 in place of direct ground. Upon hearing the tone` in his receiver the calling subscriber knows that he can proceed to dial the number of the desired line.

The general operation of selectors such as SI and S2 is well known and hence may be explained rather briefly. Responsive to the dialling of the first digit the line relay |24 is deenergized a number of times and sends a series of impulses to the vertical magnet |28. The magnet |29 responds to theseimpulses and steps up the shaft carrying wipers |3||34 until they stand opposite the level corresponding to the digit dialled.

operates in buzzer fashion to rotate the wipers |3l|34 in search of an idle trunk line. When an idle trunk line is reached, assumed in this case to be the trunk line extending to the second selector S2, the test wiper |34 will nd a battery potential on test Contact |38 and the electropolarized test relay |21 will energize in series with the changeover relay |52 of the second selector. On energizing, relay |21 breaks the circuit of the rotary magnet to stop the rotary movement. Relay |21 also extends the holding circuit forward by connecting conductor |23 to the test wiper |34. This short circuits the upper winding of relay |21 but the relay holds up by means of its lower polarizing winding. In addition, relay |21 extends conductor |20 forward to wiper |33, and closes a bridge across wipers 3| and |32.

Upon the seizure of the second selector S2, as described in the foregoing, the relay |52 energizes as previously mentioned; The line relay |50 energizes also, due to the bridge across wipers |3| and |32 at the ilrst selector SI. The line relay closes acircuit for the slow-acting relay I5 I. This is the usual release relay, but in the present case it does not ground the holding circuit because ground is fed forward from the first selector Sl.

The calling subscriber may now dial the second digitV of the called number, causing a second series of -deenergizations of the line relay |24. Each time the line relay falls back it breaks the bridge across wipers |3| and |32 at contact |39, and thus the digit is repeated on to the second selector S2 by producing a series of interruptions in the circuit of line relay |50. Under control of line relay |50 the selector S2 is operated and the wipers IGI-|64 are first stepped up vertically and are then rotated in search of a trunk line leading to an idle connector. Assuming that the connector C, Fig. 2, is the first connector found idle, when test wiper |64 reaches test contact |68 it finds a battery potential and the test Vrelay |53 energizes in series with relay 201 of the connector C. On energizing, relay |53 opens the rotary magnet circuit, extends the holding circuit forward by connecting it to test wiper |64, and locks itself to the holding circuit. Relay |53 also disconnects the line relay |50 and extends the repeating loop forward to wipers |6| and |62.

Upon the seizure of the connector C, therefore, the line relay 20| energizes, as well as relay 201, its lower winding getting its ground connection from the now grounded holding conductor 2|6, and closes a circuit for the release relay 202. On energizing, relay 202 prepares the vertical magnet circuit at 225 and at 222 it connects another ground to the holding conductor 2|6.

The calling subscriber may now dial the third digit of the number, which is repeated by the line relay |24 of the selector S| to the line relay 20| of connector C. Line relay 20| accordingly deenergizes a plurality of times and sends a series of impulses to the Vertical magnet 2|| over a circuit extending from ground at 22| by way of 225, 216, 241, 239, and winding of 2|| to battery. The vertical magnet 2|| responds to the series of impulses and steps up the shaft carrying the set of wipers 282,-284 and the set of wipers 28E- 281. The connector C has a capacity of 200 lines and has two sets of wipers. The slow-acting relay 205'is energized in parallel with the vertical magnet 2|| and remains operated during the series of impulses. Upon the first vertical step of the switch the'oi-normal springs are shifted, and

the initialenergizing circuit of relay-f2 01, is broken. The relay is held up, however-,overa circuit extending from groundzby way .of v224, `123|, 232, l230, .and Winding .of 201 .to battery.

At the end-.oi the verticaloperation, theslow- .acting relay '205 deenergizes, followed by thedeenergization of relay 201. Thelatter relay transfers the .impulse circuit `.from vertical magnet -.2:|.| to rotary magnet 2|2 vat 23.9.

. The calling vsubscriber may vnowdial .the fourth digit of the called number, and the digit .is repeated as before to the 4line relay 20 I.. This relay now vsends a seriesof impulses to fthe rotary magnet 2|,2 .over the circuit-groundat 22|., 225,121.6, .241, 239, 26.2, 21 I, and 21.2 to battery. The rotary magnet responds `and ,rotates the rtwo wiper .sets of the connector in on ,the .bank Vlevels .selected by the vertical movement, the upper set of wipers 282---284` engaging the `contacts 29.0-292 of the line of station B. Relay v205 energizes in Vparallel with the rotary magnet, .and `closes a circuit for relay 2|0, said circuit lextending from .ground at.

224 by .way of 26|, 232,238, resistance .288, .and upper winding of 2|;0 to battery. Relay 2|,0 is a two-step relay and onlycloses its .contacts 210 and 211 when energized over the above circuit. At the end of the .rotary movement relay ..205 falls back and closes acircuit for fully operating relay 2|0, the circuit extending from ground .at v221| by way of 261|, contacts controlled by 232, `210, and upper winding `of relay 2| 0 to battery. Relay 2|0 now operates fully, .locks itself at 265, Aand at 211| `shiits the impulse circuit Vfrom the rotary magnet 2I2 to the relay .209. It will be Ynoted also that relay 2z|0 disconnects the wiper set `202--284 and connects up wiper set 285-281.

The calling subscriber may now dial Ythe nal digit of the called number. The nal digit is either thedigit one or vthe digit two, which respectively select the wiper sets 285281 and 282-234. In .the present case the called line is reached by way yoi? Wiperset 218.2-284 Vand hence the final digit is two. vWhen the line relay responds, the first impulse :is transmitted to ithe lower winding of relay 209, the impulse circuit having been transferred from lthe rotary `magnet by relay 240. Relay .209 is also a two-step relay and only closes its contact 260 responsive to the impulse. When the impulse is over, the :relay A20.0 operates .all the way, due to energization `of both windings in seri-es, and `at 262 transfers the impulse circuit to the `lowerwinding of `relay 21.0. The second impulse now cornes in and .causes the deenergization of relay 2|0, due to vthefact that the two windings of the relay oppose each other. Contacts 210 and 212 break at substantially the same time. With relay 2 I0 deenergized the wiper set 282-284 is again connected. `It will be evi- `dent that if the last `digit had been one instead of two, relay 2| Uwould have remained energized, and wiper set 2357281 would have `remained connected.

Relay 209, whichis 'always-energized on the lastdigit, disconnects ground from contact group 232 at 26|, and closes a point `in the test circuit at 249. Relay i205 isenergized during the dialling of the last digitgand asjsoonas relay 209 operates, thetestcircuit `iscompleted iirst to test wiper 286 and Athen to test wiper 283, vthe latter test wiper being substituted for lthe former by the falling back ofrelay .2.I0 on-the second impulse. The test circuit may be traced from test wiper 283by way'of 261|, 249,upperzwindingofrelay `208, 23|, resistance `209, and winding of test relay 203 to battery. .If the :line of .station Bis busy .therewill be a ground potential .on test contact 29| and relay '1203 will be energized, operating only part way, however, suicient to close contact 215. Resistance 299 is high enough to prevent the energization of relay 208 and to prevent the full operation of relay 1203. At the end of the final digit relay 205 .falls back, the resistance 289 in the test circuit is cut out, and a branch circuit is substituted `for the resistance. This lowers the .resistance ofthe test circuit suicient to operate `relays 208 and 203. The former relay is slow to operate, however, and relay 203 operates and locks itself ,at .2.14, breaking the test circuit at the same time, before relay 208 can get started. In energized position, relay 203 opens the impulse circuit at 2:16, andccnnects a source of busy signalling current tothe talking conductor 2I5 at 213. As will appear .subsequently the calling line has 4already or shortly will be extended through to the 4connector C. Inieither case he will hear the busy signal and will understand that the called line is engaged.

Assuming now that the called line is idle, when .the test vcircuit is .established .as described in the foregoing, the test relay 203 will not be energized,

due to absence of ground potential at test contact 219|. When relay 205 falls back therefore a circuit will be closed which extends :from ground at 223 by way of 2.1.5, 25|, upper winding of 208, 249, 254, 283, 29|, and winding of cut-,oi relay 293 to battery. Relays 208 and '293 energize inseries over the above circuitand the latter relay disconnects the :line relay 291i. Relay :20.8 energizes over 4the series circuit sufficient to close its contact 245, and then operates all the way due .to energization of its lower winding. In `energized position relay 208 breaks the impulse circuit .at A221 .and grounds the test wiper .283 at 2M. Relay 20S also closes the ringing circuit at 24.! and 228, andat 242 connects a source of ring-back tone to the talking circuit.

Leaving `the connectorC in this condition, 4with .the kbell at station B ringing, attention maybe directed tothe operation of the confluence switch CS, which begins at the moment the `connector C i is stepped oi normal responsive to the third digit dialled. When the o normal springs are shifted on the `iirst vertical step of 'the connectora V.connectionisestablished between conductors II1I and '219, com-pletinga circuit for relay I9 .of the .trunk circuit "IC, which extends from `the grounded holding circuit including conductor 33 `.by way of 3 8, Winding of I9, 34, |03, |20, |33, |31, |63, |101, `|"liI, off-normal contact, 2I.9, side-switch SS in -rst position, and winding of Vertical .magnet :60

to battery. Relay vI9 is energized over the above circuit, magnet 60 being unaffected due to the relatively high resistance of relay I9. On energizing, `relay .I9 locks itself Aat 4I and cuts `oit its original energizing circuit, which is connected to contact spring 23 of the sender SD `at 42. Relay :I9 also closes a circuit for the stepping magnet 20 ofithe sender at .40.

The stepping magnet 20 interrupts .its own-circuit and accordingly begins to operate in the manner of a buzzer to rotate the shaft carrying the cams :2| and `22. On the first step cam 2| shifts the spring .46, thereby lsubstituting ,a .local ground connection for the circuit through-contact 4.0 of relay I9. This operation insures that `the sender magnet "20 will drive the cams through a complete revolutionand return `them to normal; even if the calling subscriber should hang up.

Asrthe cam 22 rotates, thespringZ-l rst encounters the :projections M, `which Lforce spring 23 twice into engagement with ground spring 44 and thus send two impulses to the vertical magnet Iil!) of switch CS over the circuit: ground, 44, 23,

includes sufcient resistance so that magnet 09,

is not affected, but the alternating current relay 58 responds to the impulse and operates the private magnet 62. The operation and release of magnet S2 advances the wiper of side switch SS one step by means of the usual escapement.

Further rotation of cam 22 causes projection 49 to engage spring 23, and another ground impulse is transmitted, causing the operation of the yrotary magnet 6|. Magnet 0| rotates the switch shaft one step and brings the wiper set 53-55 into engagement with bank contacts SI1-52.

As cam 22 continues its rotation, the spring 23 falls successively into the notches 1 I, sending out two alternating current impulses. These impulses cause two operations o f relay 58 and private magnet 62, and the wiper of side switch SS is advanced two steps so as to connect with relay 51. Further movement of the cam now sends a single nal ground impulse by means of projection 12, which operates relay 51. Relay 51 is a connecting relay and extends the trunk conductors 2I5, 2 I6, and 2 I8 back to the wipers 53,54, and 55. Relay 51 also locks itself to the holding conductor 2I6 and disconnects conductor 2|0 from conductor |12.

The cams 2| and 22 reach their normal position shortly after the last impulse is transmitted and spring 46 falls into the notch in cam 2 I, thus stopping the operation of the stepping magnet 20. In the meantime relay I9 has fallen back, so that the sender is not restarted. When relay 51 energizes responsive to the last impulse a circuit is completed for relay I8, said circuit extending from the grounded holding conductor 2|6, by way of contacts of 51, 54, 5|, and winding of I to battery. Relay I8 energizes and completes the final holding circuit at 39, disconnecting conductor 33at the same point. Relay I8 also unlocks relay I 9 at 38, and at its upper and lower contacts disconnects the conductors 3| and 32.

The latter operation initiates the release of the switches in Fig. 2. The line relay |24 falls back followed by relay |25. Thus a circuit is closed for the release magnet |30 and the selector S| is restored to normal. The deenergization of relay also removes ground from the holding circuit and relay |02 of finder F falls back, also relay |53 of selector S2. Relay |53 closes a circuit for release magnet |56 and the selector S2 is restored to normal.

It will be seen now that the calling line has been extended to the connector C by means of the confluence switch CS and that the switches FI, SI, and S2, Fig. 3, have been eliminated. The connection is held up by ground applied to 4holding conductor 2|6 by relay 202 of the connector C.

When the called subscriber at station B answers, the ring-cut-oif relay 206 energizes and locks itself at 234. Relay 206 also closes a circuit for relay 201 by way of 243 and 233, and relay 201 energizes. By the operation of relay 201 the ringing circuit is broken and the talking circuit is extended back at contacts 236 and 240, and the ring-back tone circuit is opened at 231. The back bridge relay 204 now energizes over the called line. At 229 relay 204 opens the release magnet circuit, and at.228 it gives its lower winding another ground connection by way of 235 and 240. In addition, relay 204 disconnects the line relay 20| from conductors 2|5 and 2|8 at 221 and 230 and substitutes for the line relay the battery feed relay 200. This completes the talking circuit, and also reverses the direction of current flow in the calling line. Relay 200 energizes and at 220 closes a local circuit for line relay 20| in order to reoperate the same and hold it and the release relay 202 energized.

The calling and called subscribers may now converse as desired, transmitter current being supplied through the windings of relays 200 and 204. These relays have ballast resistances 290 and 291 in series with them in order to maintain a substantially constant current value regardless of the length of the subscribers lines. When the subscribers are through talking they will hang up their receivers. When the receiver is' replaced at station A the battery feed relay 200 falls back, allowing the line relay 20| to fall back also. The release relay 202 then restores after an instant and removes ground from the holding conductor 2I6. This allows relays 51, I8, and I1 to deenergize. The cut-olf relay 5 also restores, and at the same time the nder F is restored in the usual manner. At the connector C the release of the switch depends on whether the called party has hung up or not. When relay 202 falls back it opens the local holding circuit at 224 and closes a point in the release circuit at 226. If the receiver is still off at station B the back bridge relay 204 will stay energized and hold open the release circuit at 229. When the receiver is replaced at station B, relay 204 deenergizes, removes ground from the locking circuits of relays 200 and 208, permitting these relays to deenergize to free the called line, and closes the release circuit at 229. Release magnet 2|3 accordingly operates to restore the connector C. The release magnet 63 of switch CS is also operated, over conductor 2I1, and restores the switch CS and its side switch SS to normal. All the apparatus is thus placed in condition for use in another call,

Some additional remarks may now be inserted with a View to a fuller explanation of certain features than appeared advisable in the course of the regular circuit explanation. To begin with, it will be understood that the sender SD is individual to the trunk circuit TC. Each' trunk circuit such as TC has a sender SD and also has a code number allotted to it which corresponds to the position of the trunk circuit in the banks of the conuence switches and which the associated sender is arranged to send out whenever it is operated. Thus the code assigned to the trunk TC is 2 I2, the sender SD always sends out this number, and any ccniluence switch operated in accordance therewith will connect with the particular trunk circuit TC and no other. If there are two-hundred trunks such as TC there will be two hundred different code numbers assigned. The cams 22 of the senders are cut in accordance with the different code numbers. There would be for instance, one-hundred cams arranged to send numbers 112 the connectors and the conuence switches.

to 002, one-hundred numbers in all, each cam having two notches 'I I providing for one hundred numbers ending in the digit two. There would also be one-hundred similar cams, except for having only-one notch 1I, providing for sending onehundredA numbers ending inthe digit one. The cams inl the two groups serve to operate switches such as CS the same, except that those sending out code numbers ending in the digit two operate relayssu'ch as 51, while those sending out code numbers having the nal digit 1 operate relays such as `56. This brings into play both wiper sets of switches such as CS and givesthe` switches access to two-hundred trunk circuits such as TC.

As statedearlier in the specification the capacity of a system having 200 trunk circuits TC is about 2400 lines. The capacity can obviously be increased by adding additional wiper sets to the confluence switches CS. For instance the switch CScould be provided with a` third set of wipers and another relay similar to relays 56 and 51. This would provide for another hundred trunk circuits TC. The cams 22 ofthe senders SD associated with the third hundred trunk circuits would be the same as the others except that they would each have three notches such as 'II.

There is a limit to the number of wiper sets that can be economically added to the coniiuence switches and consequently for very large systems a` diierentplan would be followed. An obvious arrangement is to divide the conuence switches into groups and insert group selectors between In this. arrangement each connector would be paired with a` group selector, and each group selector would have access to confluence switches in each group. The senders SD would also be arranged so as to send out four digits instead of three, the first digit serving to `operate a group selector.

In describing the operation of the system it was assumed that the connector C was completely operated by series of impulses repeated by theline relay |24 ofselector SI. In actualpractice, however, itis more or less a matter of chance that the: connector is fully operated in this manner. The operation of the coniiuence switch CS begins substantially simultaneously with the operation of the connector and each has to respond to three digits. If the calling subscriber delays a little in dialling, or if thelast three digits of the called number are of high value, the confluence switch may complete its-operation rst. If this occurs the line relay 20| of the connector is controlled over the talking path through the coniluence switch CS to complete the operation of the connector; On the other hand if the connector should complete its operation first, there is no delay in transmitting the busy tone or ring back tone to the calling party, as the repeating circuit at Si is connected with the control circuit incomingto the line relay I24by means of a small condenserY IlII.

There is a considerable advantage in starting the operation of the coniluence switch before the dialling is completed as comparedto those bypass systems in which the connection is extended clear through tothe called line before the operation of theswitch or switches which complete the talking path is started. By starting the operation of the, confluence switch at the time the operation of the connector is started the talking connection through the conuence switch is usually established by the time the called line is found, or perhaps before, and the delay which would otherwise occur is avoided. At; the same time the holding time of the switches such as SI and S2 in the setting route is reduced` to -a minimum. l

The foregoing advantages, of course, could not be secured if the connector were by-passed as well as the selectors, which brings up an additional advantage of the present system over those systems which by-pass all the directive switches used in the setting route. It is usually necessary in automatic systems to provide for different types of service among which may be mentioned regular individual line service, selective ringing party line service, code ringing party line service, and trunk service to private branch exchanges. In the ordinary automatic systems these different types of service are furnished by providing diiferent groups of connectors such as individual line connectors, selective ringing or code ringing connectors, and rotary connectors. Thus the connectors in each group are relatively simple switches as each switch only has to give one type of service. In by-pass systems where the final switches are eliminated the advantage of grouping in accordance with service facilities has to be sacrificed because the called lines are extended back to common talking links, and each link has to be of a universal type arranged to give the necessary type of service regardless of the line called. The links, therefore, are excessively complicated. In the present system the connectors are common to the setting and speaking routes, that is., only the selectors are by-passed, and the advantage of grouping the connectors for different types of service is retained. 'I'hus the connector C isone of a group of connectors arranged to provide individual line service. 'There ordinarily will be other groups of connectors for party line service, and one or more groups of rotary connectors. 'Ihese different types of connectors are well known and consequently `it is not necessary to show them in the drawings.

Since the connectors are of substantially standard types,` retaining the functions of battery feed, busy testing, ringing, etc., a. confluence switch such as CS has no functions to perform except that of completing the nal talking connection between the connector used to iind the called line and the trunk circuit to which the calling line is connected, and consequently these confluence switches are ofrvery simple construction.

As indicated hereinbefore, the connector C is in general not new, but it has a special feature involving the prevention of clicks at the calling station which is believed to be novel. This feature may be regarded as an improvement on my prior Patent No. 1,376,848, May 3, 1921. The arrangement involves the provision of a battery feed relay 20B which is connected to the talking circuit on the opposite side of the condensers from the back bridge relay 204, and the provision of contacts on the back bridge relay for connecting the incoming trunk conductors 2I5 and 253 to the battery feed relay in place of the line relay. This circuit not only greatly reduces the click or bang due `to reversal of current in the calling line, a result obtained in my prior patent, but it also eliminates the clicks due to the action of the switching through and ring cutoff relays, one or the other'of which is present in systems using standard connectors. The elimination of the ring cut-off and .switching through clicks is due to the fact that inthe present circuit the incoming trunk conductors 2 I5 and 2 I8 are normally entirely separate fromrthe talking circuit in the connector and extend only to the windings of line relay 201. When the back bridge relay operates to disconnect the trunk conductors from the line relay and connect them instead to the battery feed relay 200, it connects these trunk conductors to the talking circuit at the same time.

The invention having been described, what is considered to be new and is desired to be protected by Letters Patent will be set forth in the following claims.

What is claimed is:

1. In a telephone system, means including a finder, a rst selector, a second selector, and a connector for extending a call from a calling line to a called line, a confluence switch for bypassing both the first and second selectors, thereby directly connecting the nder and connector, and means for releasing the first and second selectors while the calling and called lines are maintained in talking relation through the finder, the confluence switch and the connector.

2. In a telephone system, a trunk circuit, means for extending a calling line to said trunk circuit, means including selector switches and a connector for selecting a called line, a confluence switch for connecting the connector with said trunk circuit, a sender individual to the trunk circuit for operating said confluence switch to connect the connector switch with the trunk circuit and for maintaining such connection, and means for releasing said selector switches after the connector and trunk circuit have been connected.

3. In a telephone system, a plurality of serially related automatic switches controlled over a calling line to select a called line, a confluence switch for setting up a by-pass connection from the calling line to the final switch, means for starting the operation of the confluence switch concurrently with the final switch, and means for completing the operation of the final switch over the by-pass connection if said connection is established before the called line is selected.

4. In a telephone system, a setting route involving selector switches and a connector switch, a speaking route excluding said selectors but including said connector, and operating means in said connector controllable either over said setting route or said speaking route.

5. In a telephone system, a setting route involving selector switches and a connector switch, a speaking route excluding said selectors but including said connector, means Vfor starting the operation of said connector over said setting route, and circuit arrangements whereby the operation of said connector may be completed over said speaking route.

6. In a telephone system, a setting route involving selector switches and a connector switch, a speaking route excluding said selectors but including said connector, means for starting the operation of said connector over said setting route, means for concurrently starting the establishment of the speaking route, and means for completing the operation of said connector over the speaking route in case the same is established before the connector is fully operated.

'7. In a separate setting and speaking route system, a coniiuence switch for completing the speaking route, a control circuit for said switch included in the setting route, and means for transmitting both direct current impulses and alternating current impulses over said circuit to control the operation of said switch.

8. In a separate setting and speaking route system, a confluence switch for completing the speaking route, a control circuit for said switch included in the setting route, said switch having primary and secondary operating movements, means for sending direct current impulses over said circuit to control said switch in its operating movements, and means for sending alternating current impulses over said circuit to control the changeover in said switch from its primary movement to its secondary movement.

9. In a separate setting and speaking route system, a nal connector, a confluence switch for completing the speaking route and individual to said connector, an operating circuit for said confluence switch, and means responsive to the beginning of the operation of said connector for.

completing said operating circuit.

10. In a separate setting and speaking route system, a connector switch for connecting with a called line, means including a train of selector switches for selecting and operating said connector from a calling line, a confluence switch associated with said connector for connecting the same with the calling line over a talking path excluding said train of switches, means in said connector for testing and ringing the called line, and means in said connector for supplying talking current for both the calling and called lines.

l1. In a telephone system, a setting route involving selector switches and a connector, a speaking route involving a confluence switch and said connector, a control circuit included in the setting route over which a calling subscriber transmits impulses to operate said connector, a second control circuit included in said setting route, and a sender operating concurrently with the subscribers calling device to send impulses over said second control circuit in the same direction as the impulses in said first control circuit and effective to operate said confluence switch.

12. In a telephone system, a setting route including a selector repeater and a connector, means for operating said connector under control of said selector repeater, a speaking route including said connector but excluding said selector repeater, means for starting the establishment of the speaking route while the connector is operating, and means effective if the operation of the connector is completed before the speaking route is established for transmitting tone currents back over the setting route from the connector to the calling subscriber.

13. In a connector switch, talking conductors each including a condenser, a battery feed relay and a back bridge relay bridged across said talking conductors on opposite sides of said condensers, a line relay, incoming trunk conductors normally connected to said line relay and disconnected from said talking conductors, and contacts on said back bridge relay forvdisconnecting said trunk conductors from said line relay and for connecting them to said battery feed relay.

14. A connecting switch as claimed in claim 13, characterized by the provision of contacts on the battery feed relay for holding the line relay energized after the trunk conductors have `16. In a telephone system, a connector switch lincluding operating means, a setting route including selector switches and said operating means, a speaking route including said operating means and excluding said selector switches,

said routes being adapted-to be `completed following the initiation of a call thereover, means for starting the operation ofsaid operating means over said setting route, and means for completing the operation of said operating means over said speaking route.

17. In a separate setting and speaking route ments and to start theother of said movements. 10

BERNARD D. WILLIS.` 

